fix(release): support validated per-run SSH address family

docs/operations/RELEASE_CONSOLE.md

@@ -58,6 +58,45 @@ checkouts remain usable for read-only planning, but every durable executor
 fails closed there; clone the registered origins into a private workspace
 before releasing.
 
+For a host with a confirmed IPv6 connection timeout, set
+`GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY=inet` only for the release-tool invocation.
+When unset, the original SSH command is preserved, including the trusted
+operator's per-host `AddressFamily` configuration (normally `any`). Explicit
+values accepted by the shared source/tag Git helper are exactly `any`, `inet`
+(IPv4 only), and `inet6` (IPv6 only). Empty, misspelled, whitespace-padded, or
+injected values fail before Git starts. The selector only adds the corresponding
+fixed SSH `AddressFamily` option: it does not change DNS, host-key verification,
+the registered remote, authentication, `BatchMode=yes`, or `ConnectTimeout=8`.
+Arbitrary `GIT_SSH_COMMAND` overrides remain ignored. For example, start a
+single local console invocation with:
+
+```sh
+GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY=inet \
+  ./.venv/bin/python tools/release/release-console.py
+```
+
+The same process-scoped setting applies to canonical source/tag readbacks and
+registry-candidate source verification. Under Flatpak, pass it explicitly to
+the host invocation with `flatpak-spawn --host /usr/bin/env
+GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY=inet ...`. It is not a global SSH setting
+and does not affect the website publisher's separate transport sanitizer, npm,
+or HTTP downloads. An IPv4-only setting cannot reach IPv6-only hosts; omit it
+or use `any` when the diagnosed restriction no longer applies.
+
+Deutsch: Bei einem bestätigten IPv6-Verbindungs-Timeout kann für genau einen
+Release-Werkzeugaufruf `GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY=inet` gesetzt werden.
+Ohne diese Variable bleibt der bisherige SSH-Befehl einschließlich der
+vertrauenswürdigen Host-Konfiguration unverändert (normalerweise `any`).
+Explizit zulässig sind ausschließlich `any`, `inet` (nur IPv4) und `inet6`
+(nur IPv6). Andere oder leere Werte werden vor dem Git-Aufruf abgewiesen.
+DNS, Hostschlüsselprüfung, registrierte Quelladresse, Authentifizierung und
+Zeitlimit bleiben unverändert; frei vorgegebene SSH-Befehle bleiben gesperrt.
+Unter Flatpak die Variable ausdrücklich an den Host-Aufruf übergeben. Die
+Auswahl gilt für den gemeinsamen Git-Helfer der Quell-/Tag-Prüfungen, nicht
+für den separaten Website-Publisher, npm oder HTTP-Downloads. Sie ändert keine
+globale Konfiguration. Nach Behebung des Netzwerkproblems die Variable
+weglassen oder auf `any` setzen; IPv4-only erreicht keine IPv6-only-Ziele.
+
 The runtime itself is part of the authority boundary. Durable run creation
 verifies the meta checkout, release/check tooling, repository registry, Python
 environment, loaded `govoplan_core` and cryptography packages, and Git/SSH

tests/test_release_git_state.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from pathlib import Path
+import shlex
 import subprocess
 import sys
 import unittest
@@ -17,6 +18,80 @@ from govoplan_release import git_state  # noqa: E402
 
 
 class ReleaseGitStateTests(unittest.TestCase):
+    def test_unset_ssh_address_family_preserves_original_command_and_operator_config(self) -> None:
+        environment = git_state.sanitized_git_environment({})
+
+        self.assertEqual(
+            [
+                "/usr/bin/ssh", "-o", "BatchMode=yes", "-o", "ConnectTimeout=8",
+            ],
+            shlex.split(environment["GIT_SSH_COMMAND"]),
+        )
+        self.assertNotIn("GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY", environment)
+        self.assertEqual(environment, git_state.sanitized_git_environment(environment))
+
+    def test_ssh_address_family_accepts_only_fixed_choices_and_survives_resanitizing(self) -> None:
+        for family in ("any", "inet", "inet6"):
+            with self.subTest(family=family):
+                environment = git_state.sanitized_git_environment({
+                    "GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY": family,
+                    "GIT_SSH_COMMAND": "/attacker/ssh -o StrictHostKeyChecking=no",
+                    "GIT_SSH": "/attacker/ssh",
+                    "PATH": "/attacker/bin",
+                })
+
+                self.assertEqual(
+                    [
+                        "/usr/bin/ssh", "-o", "BatchMode=yes", "-o", "ConnectTimeout=8",
+                        "-o", f"AddressFamily={family}",
+                    ],
+                    shlex.split(environment["GIT_SSH_COMMAND"]),
+                )
+                self.assertNotIn("GIT_SSH", environment)
+                self.assertEqual("/usr/bin:/bin", environment["PATH"])
+                self.assertEqual(environment, git_state.sanitized_git_environment(environment))
+
+    def test_invalid_ssh_address_family_is_rejected_before_git_runs(self) -> None:
+        for invalid in (
+            "", "INET", "ipv4", " inet", "inet ", "inet\n",
+            "inet; touch /not-executed", "inet -o StrictHostKeyChecking=no",
+            "$(not-executed)",
+        ):
+            with (
+                self.subTest(value=invalid),
+                patch.dict("os.environ", {"GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY": invalid}),
+                patch.object(git_state.subprocess, "run") as run,
+            ):
+                with self.assertRaisesRegex(
+                    ValueError, "GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY must be any, inet, or inet6",
+                ):
+                    git_state.git(Path("/workspace/govoplan-core"), "status", "--porcelain")
+                run.assert_not_called()
+
+    def test_source_provenance_readback_keeps_family_but_discards_ssh_command_override(self) -> None:
+        from govoplan_release.source_provenance import inspect_remote_tag
+
+        completed = subprocess.CompletedProcess(
+            [], 0, f"{'a' * 40}\trefs/tags/v1.2.3\n{'b' * 40}\trefs/tags/v1.2.3^{{}}\n", "",
+        )
+        with (
+            patch.dict("os.environ", {
+                "GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY": "inet",
+                "GIT_SSH_COMMAND": "/attacker/ssh -o StrictHostKeyChecking=no",
+            }),
+            patch("govoplan_release.repository_tag.subprocess.run", return_value=completed) as run,
+        ):
+            result = inspect_remote_tag(
+                path=Path("/workspace/govoplan-core"), remote="origin",
+                remote_url="git@git.add-ideas.de:GovOPlaN/govoplan-core.git", tag="v1.2.3",
+            )
+
+        self.assertEqual("b" * 40, result.commit)
+        self.assertEqual(
+            "/usr/bin/ssh -o BatchMode=yes -o ConnectTimeout=8 -o AddressFamily=inet",
+            run.call_args.kwargs["env"]["GIT_SSH_COMMAND"],
+        )
+
     def test_manifest_version_does_not_confuse_interface_versions(self) -> None:
         from tempfile import TemporaryDirectory
 

tools/release/govoplan_release/git_state.py

@@ -197,6 +197,13 @@ def sanitized_git_environment(
     """Keep only deliberate process/auth inputs and neutralize Git redirection."""
 
     environment = os.environ if source is None else source
+    address_family = environment.get("GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY")
+    if "GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY" in environment and address_family not in (
+        "any", "inet", "inet6",
+    ):
+        raise ValueError(
+            "GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY must be any, inet, or inet6"
+        )
     result = {
         key: environment[key]
         for key in (
@@ -221,6 +228,10 @@ def sanitized_git_environment(
             "PATH": "/usr/bin:/bin",
         }
     )
+    if address_family is not None:
+        result["GIT_SSH_COMMAND"] += f" -o AddressFamily={address_family}"
+        # Preserve only an explicit, validated choice across re-sanitization.
+        result["GOVOPLAN_RELEASE_SSH_ADDRESS_FAMILY"] = address_family
     return result